LYMAN: STUDIES OF HYMENOMYCETES. 
127 
The Nature of Polymorphism among the Basidiomycetes. 
The primary reproductive body of the Basidiomycetes is the basidio- 
spore, borne on the basidium, which is the characteristic organ of the 
group. All other spore forms, i. e., those not borne on basidia, will 
be classed in this paper as secondary or imperfect spores. No con¬ 
sideration will be given to purely vegetative multiplication due to the 
spreading of the mycelium in the substratum, or to the formation of 
such enduring parts as rhizomorphae, etc. Nor will the production 
of sclerotia by many species receive attention here save in the case of 
the small definitely formed bodies which Eidam called bulbils. These 
are reported for the first time in this paper as occurring among the 
Basidiomycetes. Secondary spores thus far known to belong to 
species of Basidiomycetes are of four types: (a) chlamydospores,— 
encysted vegetative cells; (6) oidia,— the dissociated cells of vegetative 
hyphae; (c) budding cells,— produced by yeast-like growth; and 
(< d ) conidia,— exogenously abjointed cells which show more uniformity 
of size and shape than do the other types of spores mentioned, and are 
usually produced on more or less characteristic structures called 
conidiophores. 
In “ Kryptogamen-flora von Schliesen, pilze,” heft 1, p. 87, Schroter 
(’ 85 ) says that the polymorphism so richly shown by Ascomycetes is 
disappearing among Hymenomycetes, and the conidia still seen in 
individual cases are in process of degeneration. But Brefeld (’ 89 , 
p. 187) asserts that as a result of his extensive culture studies this 
view must be abandoned, since Basidiomycetes are in no way inferior, 
as regards polymorphism, to Ascomycetes or other classes of fungi. 
Both of these views seem extreme in the light of our present knowledge. 
The investigations of Brefeld and others have revealed a considerable 
number of imperfect spore forms (largely oidia and chlamydospores) 
not known to Schroter, but the number and variety of well differen¬ 
tiated forms, at least among the Autobasidiomycetes, do not appear 
to warrant Brefeld’s statement. Among the Phycomycetes and 
Ascomycetes, secondary spore formation is probably present in the 
majority of species; the secondary spores are produced in immense 
numbers and in varied fashion, and are of such great importance in 
reproduction that in many species the formation of zygospores or 
ascospores is resorted to at certain times only, or under special condi- 
